Hard disk drive incorporating rotating magnetic disks is commonly used for storing data in the magnetic media formed on the disk surfaces. Typically, magnetic heads embedded into sliders used in the hard disk drive are those having a structure in which a reproducing (read) head having a magnetoresistive element (that may be hereinafter called an MR element) for reading and a recording (write) head having an induction-type electromagnetic transducer for writing are stacked on a substrate.
For read heads, giant magnetoresistive (GMR) elements utilizing a giant magnetoresistive effect have been practically used as MR elements. Conventional GMR elements have a current-in-plane (CIP) structure in which a current used for detecting magnetic signals (that is hereinafter called a sense current) is fed in the direction parallel to the plane of each layer making up the GMR element. Another type of GMR elements have a current-perpendicular-to-plane (CPP) structure in which the sense current is fed in a direction intersecting the plane of each layer making up the GMR element, such as the direction perpendicular to the plane of each layer making up the GMR element. Another type of MR element is tunnel magnetoresistive (TMR) element, which also has a CPP structure and has become the mainstream MR element due to its more remarkable change of MR ratio by replacing GMR element.
FIG. 1 shows a detailed structure of a conventional CPP-TMR element read head, as shown, the read head 10 includes a first shielding layer 111 formed on a substrate 110, a second shielding layer 114, and a TMR element 112 sandwiched between the first and second shielding layers 111, 114, and a pair of hard magnets 113 formed on two sides of the TMR element 112. Concretely, the read head 10 may include antiferromagnetic (AFM) materials (not shown) within or near the TMR element 112. The TMR element 112 is a multiple-layer structure which includes a free layer (not shown) having a magnetization direction changed by an external magnetic field.
As known, the read head including the AFM materials, and/or the hard magnets 113, and/or the shielding layers 111, 114, and/or the free layer can be affected by temperature. For example, for the AFM materials, which have no magnetism due to their inner magnetic moment directions counteracting each other, however under a high temperature, the inner structure and the material characteristic of the AFM material may change and become unstable, the magnetic moment directions may change and be disordered for example. For the free layer, the high temperature will bring noises which also will affect the stability of the free layer, and in turn weaken the performance of the TMR element 112.
According to the conventional manufacturing method of sliders with the above-mentioned magnetic heads, typically, a wafer provided with many magnetic head elements is first cut to separate into a plurality of row bars each of which has a plurality of slider elements aligned. Then, each row bar is lapped so as to adjust its element height to a defined size. One important lapping surface is that the medium facing surface for each slider element which is called an air bearing surface (ABS). Concretely, the row bar is pressed to a rotating lapping plate at a predetermined pressure to lap the ABS of the row bar to a predetermined requirement. Finally, the row bar is cut into a plurality of individual sliders.
Inevitably, a local high temperature will be generated on the lapping surface during the lapping process. As mentioned above, the read head including AFM materials, and/or hard magnets 113, and/or shielding layers 111, 114, and/or free layer may be affected by temperature easily. And since the magnetic moment directions of the AFM materials or other elements are aligned either parallel or perpendicular to the ABS of the row bar, therefore when the local high temperature is generated on the ABS, the magnetic moment directions of the read head will be disordered, somehow like annealing effect without align magnetic direction, which will affect the performance of the magnetic head. On the other hand, high temperature noises may be generated on the free layer under the local high temperature, which cause the performance of the magnetic head unstable. As a result, unstable sliders such as with high temperature noise, hysteresis and bad characteristic curve with serious jumps may be produced. Finally, the function and performance of hard disk drives may be weakened.
Hence, it is desired to provide an improved manufacturing method of a slider and manufacturing apparatus thereof to overcome the above-mentioned drawbacks.